Electrical system



IR. C. MOORE ELECTRICAL SYSTEM Filed June ll, 1951 March 2, 1954 Patented Mar. 2, 1954 ELECTRICAL SYSTEM Robert C. Moore, Erdenhem,

Pa., assignor to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvania Application June 11, 1951, Serial No. 230,889

10 Claims.

The present invention relates broadly to systems for displaying information in visible form.

More particularly, it relates Ito cathode-ray tube systems which are supplied with a signal having diiierent portions representative of different types of intelligence and which utilize this signal to control the intensity of the cathoderay beam at the same time that the latter is swept across intervals of the cathode-ray tube screen adapted to display the aforesaid diiierent types of intelligence. In such systems, accurate registry between the occurrence of intelligence representative portions of the signal and display intervals is clearly of paramount importance.

Systems which operate in the aforesaid manner are strikingly exemplied by the so-called dot-sequential color television systems, which are characterized by the employment of transmitted signals whose amplitude is, in rapid succession, indicative of three primary color componente, such as red, -green and blue, for example, of minute adjacent elements of a televised scene. To obtain such a signal, the scene to be televised may be viewed simultaneously by three different television cameras, respectively equipped with red, green and blue optical iilters. These cameras scan the scene in synchronism and produce continuous video output signals whose respective amplitudes vary in accordance with the corresponding color content of the scene. These three output signals are then successively sampled, each at a very high rate, such as, for example, 3.5 million times per second, after which the sampled signals are combined and iiltered so as `to reject all signal components having a frequency above, say, 4 megacyc'les. The

composite signal resulting from these various operations has a low frequency amplitude-varying component corresponding to the average brightness of the televised scene, and a high frequency component of 3.5 megacycles nominal frequency, but modulated in amplitude and phase in accordance with the coloration of the scene. At three time spaced intervals during each cycle of this 3.5 megacycle component, the total amplitude of the composite signal will thus be representative of information respecting the red. green and blue color components respectively of the televised scene. With the .present standard horizontal scanning rate of cathode ray tube receivers at 15.75 kilocycles, this corresponds to approximately 186 intervals, during each horizontall sweep traversal of the receiver tube beam, at which the received signal is representative of any one color component,

`Receiver systems are known, for use with such dot-sequential systems, which include a cathode ray tube having a screen on which minute phosphor elements are adjacently deposited in such a manner that every third element emits, in response to electron beam impingement thereon, light of one primary color, say red, for example, while the intervening elements emit green and blue light, respectively. The electron beam is then intensity-modulated by the received video signal and deflected across these elements so that it successively traverses all of the elements lying across the path of each horizontal scanning line.

One coniiguration which these screen elements have frequently been given is `that of narrow stripes whose longer dimensions extend transversely to the direction of the horizontal scanning lines.

Proper color rendition of the televised scene was obtained with this transversely striped screen only if the electron beam was incident upon a stripe emissive of a certain color at exactly the same interval at which the beam intensity modulation was representative of intelligence respecting that color or, which is the' same thing, when the received signal was representative of such intelligence.

Diiliculties were encountered in the practical realization of this objective because of nonlinearity of the cathode ray -tube sweep circuits, unequal spacing of the light-emissive stripes across the scanning lines, and variations in the rate of occurrence of intelligence representative portions of the received signal proper due to varying phase delay in the transmitter-receiver path.

To overcome these diiculties, there Were provided means for deriving, from the cathode-ray tube screen structure, indications of beam impingement upon certain phosphor stripes. These indications were then utilized to control the horizontal scanning rate of the beam across the stripes so as tc compensate for improper color registry produced by the aforedescribed variations. Since each horizontal scan is completed in 1/ 15,750 seconds, it is apparent that very little time is available in which to effect this compensation, so that the control action must be very rapid.

Note that it is characteristic of dot-sequential systems that their transmitted and received signals are representative of intelligence respecting different colors at several intervals during each horizontal line scanning period. 'Ihis makes it necessary to dispose the receiver tube color stripes transversely -to the horizontal scanning. lines, if all of the intelligence representative portions of the signal are to be utilized.

i stierf-stripes.

deflection 'produced by There are also known so-called line-sequential color television systems which are characterized in that the transmitted and received signals are representative of intelligence respecting a single color during an entire horizontal line scanning period. To display such a signal, the differently colored stripes of. the vreceiver cathode-ray tube are arranged longitudinally of the direction of horizontal beam deflection, so that the beam re mains impingent upon a single color stripe dur.- ing any one horizontal line scan. This system is, however not suitable for the display o'fdte's'equential signals whose color representativeness changes during the scanning ofeachline. y

It is, accordingly the principal purpose of 4the invention to provide a color television receiver which receives dot-sequential televisionsignals and displays them by modulating an` electron beam scanning transversely across the color sfs retains "the superior accuracy of sftripesare'disposed longitudinally of rizontal scanning-direction.

l i anotherjo'bjectof lthe .invention tc provide imp luvd; means for monitoring cathode-ray position.indd-sequential color television :r

receivers and to utilize the monitoring. indications soi-as tof-,correct improper beam positioning.

1t-is still another object of the invention to provide-a dot-sequential color television receiver which include sfmeans for utilizing indications or cathode-ray beam position; tocontrol the vertical deflection so as -to correct-improper beam positioning. 4

'Tigris a-eaturexofapparatus embodying'my invention that color registry."isdnherentlyentirely independentzofi thelinearity-otthe-horizontal defiectionrcircuits..

. To-achieve the. 'foregoing-"obiects, 'as Wellwas others which 'will zfip1`9ear.,. I Avprovide-fthe 'cathode ray tubeo'f my receiver withfafscreenon which colrdfiliglitemissive p osphorfstripes; cyclically recurrent-.fm1 th three primary colors, vare dis-- ptsed'as n'r'ec' rsffor the line-'sequentia'lfsysti', iiael-yf'l'ngitdinall'y of the line-scanning di'ectil'i. 1 :al-lso provide -so-called' indexing str1 s 'Whose detailednature 'will :be-explained h i'riafter aridi'whichl'para'llel' the light-emissive elements at'int'ervals 'of vevery three such-phos- Nte, 'in this connection, thatline 'scanningis conventionally carried out by deiiectingthe 45'el tron'be'am of the cathoderay'tube in livio mutually perpe 'di'cul'ar directions-'by the s'ocalledl-'iorizoiital andi vertical deflection Afsysteins respectively. is wellflmown, the direction-of b'in"-fdeflection-proddced' by 'the horizontal deection system acting alone is not exactlyfthe siiie's thelrie scanning direction, but instead fc'irins'fal s'mall angle therewith. -Thedeection produced' byl thev vertical' -deiie'ctionv s'ystem,=on the other isat ri'g'htangles to thedirectionof the horizontal 'deiiection system "and forns, therefore, the' complementary elefwit -the-line'scanxiirig direction. lThnsftiie liie tscafiin'iii'g"1diriaction-is; 'in' eff ect, 'th sulta'rit of the beam ciifiaiii'onsl produced-ib :fthef stripes of the cathode-ray tube screen, and which .u

erebya..dot-setiiential signal is displayed even zontal and vertical deflection systems acting jointly. As is well known, the angle between the horizontal deilection direction and the line scanning direction depends upon the ratio of the horizontal deflection rate to the vertical deflection rate, the angle becoming smaller as this ratio is increased. In accordance with the invention, this ratio, and With itithe inclination from the horizontal of the scanning lines, is chosen so that consecutive sweep traces oi the beam are separated by approximately the vertical space occupiedby three phosphor stripes and one indexing stripe. By virtue of this arrangement, the beam,fwhi`ch 4follows 'say the red stripe during its initial sweep traversal of a scanning field, will thereafter follow the red stripe oi each group of three di-ifferentlycolor-emissive stripes, as accuratelyvas the sweep linearity will permit.

Further in accordance With the invention, there is superimposed, upon the deflection produced by one of these systems, 'rapidly reciprocating auxiliary deflection o'fconstant amplitude andv of a frequency substantially equal to the rate of recurrence of intervals at which the received signal is representative 'of intelligence respecting one particular color, The amplitude o'this auxiiia'ry deflection chosen so that it 'extends over the space occupied by threead'jacent'phosphor stripes and at least 'one indexing stripe, 'this 'space being measured inthe 'direction of auxiliary deflection. `While this is not essential 'to 'the realization of the invention, for reasons which will appear, the auxiliary deii'ection direction is preferably chosen parallel to the vertical deflectiony direction. a result 'of the application'of this auxiliary d eiiecti'on the beam Will' not only traverse its'norm'al horizontal scanning .path diie to the combined action of the conventional horizontal and' vertical deflection systems but'vvill, in addition, carry'out a reciprocating vertical displacement across a group of three diiierently colored` light'erriissi've screen elements. By selecting this auxiliary delection frequency as hereinbefor'e specified, the beam isv now made to traverse three differently colored light-emissive elements during the time of occurrence ,of` three consecutive signal intervals at which the signal is representative of information vrespeating.thefth'ree diierent primary colors. Ing-the illustrative rcasehereinbeiore assumed, in which the longitudinal and vertical deflection systems1 were so proportioned' as to sweep. the bea-rn along consecutive. red. emissive phosphor stripes,v this auxiliary deiiection.\vili then repeatedly: deiiect the beam from itsVv path along the red stripe, causing it, during each deecti'on cycle, to traverse thence-rest green, bluev and indexing-stripes as well. Since this auxiliary deflection is of relatively small'amplituda it i's an 4easy'-matter'to-give it such form that the beam -will traverse the diierently colored. stripes at Ithe same- 'time-v spaced-intervals at which the signal "isi-representative of `diderent color information. ands@ on Aconsecutiv'ely for the other colors and-in the same-sequence; Sincethe beam,

during each 'cycle of. v-zaauriliary deflection, also traverses atleast one index-ing stripe, the desired registry: betweenf intelligence.representative portions-tof- Ithe received signal and beam incidence uponv f correspond-ingl 'colored light -ernissiveelements Will-"be evidenced by one-particula-r pattern of: the-'signals produced by the index-ing stripes. Means aire-J then; provided "for sensing departures from. this* desired pattern: andforproducingy a corrective deflection in ardinecrfiomparalleitothe miiiaioedeectibmdireetiom sofas-to. restore Lthe desired indexing signal pattern which, so long as it prevails, is conclusive indication of registry between the aforesaid signal portions and beam incidence intervals,

Note that the manner in which the auxiliary deection signal is produced is immaterial for the purposes of my invention, so long as it provides the aforedescribed beam impingement registry. In practice, however, a suitable source of such signal will be a received signal component often provided in dot-sequential color television systems and called the color synchronizing burst. This burst is a train of a few cycles of an oscillation superimposed on the trailing half of each line blanking pulse and of a frequency equal to the sampling rate. It is characterized in that its phase is independent of color information and indicative of the time of occurrence of video signal intervals respecting one particular color. Thus its frequency and phase provide a reference with respect to which color information representative signal portions may be located. In this respect, the color synchronizing bursts provide a particularly useful reference signal inasmuch as they undergo all of the varying phase delays to which the video signal is subject during transmission.

When utilizing these color bursts to produce the auxiliary deflection signal, the latter is given the same frequency as the oscillation of which the bursts consist, and a phase which is fixed relative to the phase of these oscillations.

The features and operation of specic apparatus provided for the performance of the abovedescrlbed functions will be more readily understood from a consideration of the detailed discussion which follows when taken in conjunction with the accompanying drawings wherein:

Figure 1 is illustrative of a preferred embodiment of my invention in a color television receiver;

Figure 2 is an enlarged, fragmentary view of a portion of the screen structure of the cathode ray tube usedas the signal display device in the embodiment of Figure 1 which will be useful in the explanation of certain aspects of the operation of this embodiment; and

Figure 3 shows certain important relationships between the position of elements of the screen structure shown in Figure 2 and the scanning traversal of these elements by the electron beam.

There is shown, in Figure 1, to which more particular reference may now be had, a rectangle I0, designated signal source which will ordinarily comprise such conventional components of a television receiver as the antenna, tuner, radio frequency amplifier, converter, intermediate frequency amplifier and video detector. The output of this signal source II) will then be a video signal whose amplitude is, at time-spaced intervals, representative of information respecting the red, green and blue color content of the scene being televised. At intervals of one receiver scanning line, this video signal will be briefly obliterated by a conventional blanking pulse upon the leading portion of which there is, as is usual, superimposed a horizontal synchronizing pulse, while upon the trailing portion thereof is pedestaled the aforementioned color synchronizing burst. In the exemplary case under consideration this burst is at a frequency of 3.5 megacycles. As has been indicated-'the frequency and phase of this burst provide needed information at the receiver respecting the rate of occurrence of picturejintelligence representative 'portions' of thel composite video signal'l and,

furthermore, indicate at which interval during each cycle of this color signal the latter is representative of intelligence respecting one particular color. Since the order of occurrence of the intervals at which the color signal component is representative of information respecting the different color components is usually maintained constant, the indication provided by the synchronizing burst phase respecting one of these colors is suilicient to define the times of occurrence of the portions representative of intelligence of the other two colors, inasmuch as these follow the first one in the same order and at predetermined spacings. This color synchronizing burst is utilized in practicing the invention in a manner hereinafter described.

The composite video signal which appears at the output of signal source I0, or at least such portions thereof as are representative of color information, are then supplied to conventional video amplifier II and thence to the beam intensity control grid I2 of cathode ray display tube I3, where they serve to modulate the intensity of the electron ybeam emitted by cathode I4 in the manner common to color television receivers. Cathode ray tube I3 is further equipped with a conventional accelerating anode I5 connected to a suitable source of unidirectional positive potential A+, as well as with vertical deiiection coil I6, horizontal deflection coil I1, a second anode I8 which is connected to a source of positive second anode potential A++, and a screen structure I9 whose features are described in detail hereinafter. While this particular cathode ray tube has been shown to be equipped Y with electromagnetic deflection systems, it will this case' 3 5 megacycles,

be understood that the invention is by no means limited thereto and that electrostatic deflection systems may be used in their place in accordance with the well known interchangeability between electrostatic and electromagnetic deiiection systems. At the same time that the output of signal source I0 is supplied to video amplifier II, it is also supplied to conventional horizontal deflection circuits 20 which respond thereto in the usual manner to provide a sawtooth current wave for application to horizontal deflection coils I'I which, in turn, produce deflection of the beam in a horizontal direction across the screen structure I9. The composite video signal derived from signal source Ill is also supplied to conventional vertical deflection circuits 2l which are responsive thereto to provide a suitable sawtooth wave of output current for application to vertical deection coil IS where it acts upon the electron beam of the cathode ray tube I3 to deflect the latter repetitively inavertical direction across screen structure I9. Still another circuit to which the composite video output signal of signal source Ill is supplied in color symchronizing burst separator 22. This circuit is characterized by being responsive onlyto the aforedescribed color synchronizing bursts and being substantially non-transmissive of all other components of the composite video signal. Such a separator may take any one of several known forms; for example it may consist of an amplitude separating circuit followed by a lter, the separating circuit being one which rejects all signals below the blanking pulse level, thereby eliminating all but the horizontal synchronizing'-pulses and the color synchronizing bursts immediately. The filter is designed to transmit signals ofthe sampling frequency, in

to the substantial exciusionI of ail-'otl1'er signals.- -Thereby the horialmost instantaneous downward sweep of the beam during the fallingvportion of the sawtooth wave. As has been indicated, the amplitude of this wave is chosen so that the beam excursion which it produ-ces extends over a group of three adjacent phosphor stripes. Starting from any green stripe 21, therefore, the beam will sweep slowly across the next upwardly adjacent phosphor stripe, which happens to be the red stripe 26, and then across the upwardly adjacent blue stripe 28, after which it will return almost instantly to impingement upon the green stripes 21 from which its upward movement initiated.

This will appear more clearly with reference to Figure 3, where there is illustrated a single set of three adjacent phosphor stripes 26, 21 and 28, it being understood that an indexingl stripe 39 is superimposed on the central stripe 26 of the set, so that the two are indistinguishable from the particular angle of view of the figure. Different paths which the electron beam may follow during a line scanning traversal are shown in this ilgure. Broken line 31 indicates the normal sawtocth path hereinbefore described which is seen to lead generally from left to right from the bottom of green stripe 21, across red stripe 26, to the tcp of blue stripe 28, after which it returns abruptly to the bottom of stripe 21 and thence resumes its next gradual upward sweep. During traversal of red light emissive phosphor stripe 2S, the beam will, of course, also be impingent upon index stripe 30 which is superimposed thereon. As a result, the secondary emission current flowing to second anode I8 will increase considerably during the interval f beam impingement upon red light emissive phosphor stripe 26. This increased current flow will cause increased con' duction through resistor 3l, shown in Figure 1, which completes the return circuit between screen I9 and second anode I8. This surge of current is then applied, by way of pulse forming network 32, 33 to cohered oscillator 34 where it produces a substantially sinusoidal output signal having the same phase and frequency characteristics as the indexing signal derived from stripes 33. If, now, the vertical deflection produced by the main vertical deflection circuits 2l is of precisely the right value so that the path of the beam, due to auxiliary vertical deflection, is as shown by line 31 of Figure 3, then the beam can always be expected to traverse the indexing stripe 33 at the sa-me time after the inception of each cycle of auxiliary deflection, this being the equivalent of saying that the phase of the signal produced by the indexing stripe will always be constant relative to the phase of the auxiliary vertical deflection signal. Observe now that, if the main vertical deflection should take place too slowly at any timel then the beam will be vertically displaced in an upward direction from its desired initial position and this initial upward displacement will be maintained throughout its deflection by the auxiliary deflection signal. Broken line 38 of Figure 3 shows the path of the beam under these conditions and indicates that the beam will traverse indexing stripe 30 sooner after the beginning of the auxiliary deflection cycle than would normally be the case. This, in turn, will produce a premature occurrence of the indexing signal, corresponding to a phase advance or the indexing signal relative to the auxiliary deflection signal. The opposite effeet will take place if the main vertical' deflection is too rapid, for then a downward error will appear inthe beam position during its auxiliary vertical deflection, so that it will traverse indexing stripe 30 later than it would under conditions of accurate vertical deflection, thereby producing a phase delay of the indexing signal relative to the phase of the auxiliary vertical deflection signal. This condition is shown by broken line 39 of Figure 3.

Since such phase changes of the indexing signal faithfully reflected by the output signal of cohered 4oscillator 34, whereas the phase of the output signal of cohered oscillator 23 is representative, and indeed determinative of the phase of the auxiliary vertical deflection signal produced by circuits 24, these respective output signais of cohered oscillators 23 and 34 may be compared to determine both the magnitude and the sense of their relative phase variations, which have been shown to be a measure of the accuracy of main vertical beam deflection. To

put this information into useful form, the output signals of the two cohered oscillators are simultaneously supplied to the two input circuits of a conventional phase comparator 35, which is operative in well known manner to produce a unidirectional output 'potential proportional to the instantaneous phase difference between the signals from cohered oscillators 23 and 34. It is then a simple matter to utilize this output potential of phase comparator 35 to produce a deflection current in correction coil 36 of sufficient magnitude to counteract all departures of the vertical beam deflection from its desired value. For this purpose it suffices to determine the constant value of phase difference between signals from cohered oscillators 23 and 34 which corresponds to the proper Vertical deflection condition on tube screen i9 and to proportion the phase .comparator 35 in such a manner as to produce no corrective output potential when this particular` phase difference between the cohered oscillator output signals prevails. Furthermore, the phase comparatoi` may be arranged to produce a current flow through correction coil 35 which is of such polarity as to deflect the cathode ray beam additionally downward whenever the phase of the signal from cohered oscillator 34 advances with respect to the phase of a signal from cohered oscillator 23, while producing a current flow of the opposite polarity whenever the signal from cohered oscillator 34 is delayed with respect to that from cohered oscillator 23. It will be understood, of course, that additional D.-C. amplification may be provided between the output of phase comparator 35 and correction coil 36 as required.

Note, in this connection, that separate coils have been shown in Figure 1 for purposes of main vertical deflection, auxiliary vertical deflection, and correction. When such separate coils are employed, it may be necessary to bunch them very closely together due to the limited space available along the cathode ray tube neck. In that event, precautions may have to be taken to prevent interaction between the Various coils. This may be done by tuning the auxiliary deflection coil to the frequency of the auxiliary deflection signal, while tuning the correction coil to the much lower frequency range in which variations in the phase comparator output potential occur. Ordinarily, no special effort need be made to prevent interference with the main vertical deflection coil, since the latter is iron cored and therefore responsive only to the very low frequency vertical deflection signals. Alternatively,

.a-special coil may be designed for combining vthe controlled, while actual beam impingement is 7 independent of horizontal deflection and is, instead, dependent only on the auxiliary vertical delection, this latter being in turn synchronized with the times and rate of occurrence of intelligence representative signal portions by means --of-the color synchronizing bursts.

Observe that the link between phase ccmparator 35 andthe received color SJDChrOIlZng burst is` necessary only when it is contemplated that the rate of occurrence of intervals at which the received signal is representative of intelligence will not be substantially uniform. If that rate be'uniform, then a stablelocal oscillator may be the source of auxiliary vertical deflection signals and. may .likewise be connected to phase comparator v35 =to provide a reference for .deviations .in the phase of the index signal.

4Several ancillary aspects of the invention now remain to be considered.

First it will be noted that the preceding discussion has been directed to a system in which the auxiliary deflection .parallels the main vertical deflectionfand in which signals indicative of improperbeam positioning are utilized to corm rect the rate of .main Vertical deflection. This is the preferred arrangement because control of va slowly varying parameter like the vertical deilection rate promotes greater accuracy. Nevern theless, substantial improvements over prior art arrangements can still be achieved by providing auxiliaryr beam deection in. a direction. parallel to .the main horizontal delection,.in which case correction ofthe main .horizontal deflection rate must be effected.y Beyond rotating .the auxiliary .deflection coil 24a, and the correction coil 36 of 4Figurel through-a 90 angle so as to produce horizontal instead of vertical deilection, the only change required for this modified operationis a readju'stment of auxiliary deilection circuits 2'4 to produced sawtooth current Wave of sufficient amplitude to cause the beam to traverse horizontally a group 'of three adjacent vphosphor stripes of the screen structure during each cycle of` auxiliary dee'ction.

'Notefurther that, in the system hereinbe'fore described, a certain signal output from indexing stripesfllI will be produced not only during' the gradual upward deilection ofthe-beam produced bythe rising'portion ofthe auxiliary deflection wave,'but also-during theextremely rapid downward passagefo the beam across the index stripe 'duetcthe'rapidly falling portion of thisA deflection wave. Thls'latter-sig'nal will, however, be 'or extremelyshortduration, due to the fact that thefbeaniimpinges (inthe index stripes only very briefly during the falling Aportion of the auxiliar-y deection cycle. ".I'he energy content of this signal will, therefore, be extremely low so that itwill .ordinarily be unable .to affect the operationdf thel remainder of the system antiparticuiarlylthe'phasing of cohered oscillator 34, as establishedrby the phase or the indexingsign'al produced during the rising portion cfithefsawtooth wave. :If the downward'slope oi? Ithe'sawtoethauxili'ary deflection wave .is notfasfsteepais the .auxiliary deflection cycle.

hereicontemplatedf, then the beam' mayv pro-duce,

during its downward traversal of the indexing stripe, 'a signal of duration and energy content comparable to that :produced during its upward traversal of the indexing stripe. Such signals may 4improperly aiect the phasing of oscillator 34 and it will, therefore be necessary to provide auxiliary means for blanking the beam during its downward deflection interval so that no signal at all will be produced by the index stripe during downward beam traversal thereof. The same reasoning applies tc the spurious emission of red light from-.thecolor stripe 26, lying beneath index'stripe'ii, which may occur during the rapidfdownward return of the beam at the end ci? Here, again, the durationof this lightl emission will be normally so small as to bewunappreciable, but any disturbance caused thereby may again be eliminated by blanking of the beam during ,this return interval.

In fact,.such=blanking techniques maxe it feasible .to useauxiliary deilection waveshapes other than the sawtooth -wave hereinbefore contemjplated. For example, the auxiliary deflection signal may take the' "form of a sinusoidal wave, during whose downward sloping portion the cathode :ray beam may be blanked by a signal suitably delayed with. respect to the beginning of -each auxiliary ldeflection cycle. In any or" these cases where Vblanking vbecomes necessary, this may bewsimply eiected'by deriving a signal indicative of the beginningfof each auxiliary de fle'ction cycle, delaying the signal so that it oc 'curs 'at the time whenfblanking is required and then supplying the' signal toz electron beam intensity control grid I2 With such-polarity as to cut off theelectron-beam: during-the required intel4H val.

'Let it .also 'be understood, that the particular indexing 'arrangement :hereinbefore described does not form an :essential :part of my invention. Numerous other arrangements are known for producingindi'cat'ions ofielectron bea-rn iinpingement uponcertain portions of ascreen structure and any one of these may be used in a systen` embodying `the invention. For example, it is possible'to formcertain of the color stripes themselves ofamaterial'having a different secondary electron emissivity thany the remainder of the stripes. that case, 'the separate indexing stripes shown'in Figure 2' may be'dispensed with. Furthermore, .reliance on secondary electron 'emission fphenomenazmaybe avoided altogether,

- if desired, asit ispterfectly'feasiblel to derive suitable indexing .signals from a photoelectric cell which 'views the screen. structure through a filter transmissive of light of only one primary color emitted by--th Stripes.-

vIt will be" understood that numerous nflodican tions,-other'than those hereinbeiore suggested,

vwill occur tc 'those s'klllediin the art'without departing from my' inventive-concept. I therefore desire :the :scope 'of the latter to be limited only by the appended claims.

I claim:

l. In'acathode ray 'tubev display system: means for' producing a signal comprising successive pertions representativec dill-'arent intelligence conipcnents, portions representative of particular components occurring in Aa predetermined erf and recurring at a predetermined rate; a cath.- ode ray tube 'for reproducing the intelligence represented 'by'saidfs'ignaL said tube comprising afs'ourcedfaneletfonbeam, and a nuorescent screen comprising a plurality of substantially parallelly disposed phosphor strips; means for deflecting said beam in a direction generally parallel to said phosphor strips and at a rate such as to cause said beam to traverse only a portion of the length of a given strip during one cycle of said signal; means for deilecting said beam in a direction generally transverse to said phosphor strips at a rate such as to cause said beam to traverse diierent strips during successive scans in said direction generally parallel to said strips; means for producing recurring auxiliary deection of said electron beam in said direction generally transverse to said phosphor strips at a rate substantially equal to the rate of recurrence of said portions of said signal and of an amplitude suicient to cause said beam to traverse substantially the width of a phosphor strip during each cycle of said deection; means responsive to electron beam impingement on a predetermined region extending longitudinally of each said strip to produce signal indicative of said impingement; and means for utilizing said produced signal to control the instantaneous rate of deflection of said beam in said direction generally transverse to said phosphor strips.

2. In a cathode ray tube display system: means for producing a signal comprising successive portions representative of different intelligence components, portions representative of particular components occurring in a predetermined order and recurring at a predetermined rate; a cathode ray tube for reproducing the intelligence represented by said signal, said tube comprising a source of an electron beam, a fluorescent screen comprising a plurality of substantially parallelly disposed phosphor strips and a plurality of indexing stripes, each associated with one of said phosphor strips and disposed substantially parallel thereto; means for deilecting said electron beam in a direction generally parallel to said phosphor strips and at a rate such as to cause said beam to traverse only a portion of the length of a given strip during one cycle of said signal: means for deecting said electron beam in a direction generally transverse to said phosphor strips at a rate such as to cause said beam to traverse different strips during successive scans in said direction generally parallel to said strips; means for producing recurrent auxiliary deection of said electron beam in said direction generally transverse to said phosphor strips at a rate silbstantially equal to the rate of recurrence of said portions of said signal and of an amplitude sufcient to cause said beam to traverse substantially the width of a phosphor strip and to traverse the indexing stripe associated with a strip during each cycle of said deflection;

means for deriving a signal in response to impingement of said electron beam on said indexw ing stripes; and means forutilizing said derived signal to control the instantaneous rate of deiiection of said beam in said direction generally transverse to said phosphor strips.

3. In a cathode ray tube display system: means for producing a signal comprising successive portions representative of diirerent intelligence components occurring in a predetermined order and recurring at a predetermined rate; a cathode ray tube for producing visible indications of the intelligence represented by said signal, said tube comprising a screen and means for projecting an electron beam toward said screen; means for deecting said beam in first and second different directions across said screen and at rates such as to trace successively a plurality of substantially parallel paths upon said screen; a plurality of phosphor strips. each disposed longitudinally of one of said beam paths upon said screen; a plurality of indexing stripes, each associated with one of said phosphor stripes and disposed substantially parallel thereto; means for producing cyclical deflection of said beam across said screen in said rst direction at a rate substantially equal to said rate of recurrence of particular portions of said signal and of an amplitude suincient to cause said beam to traverse the width of a phosphor strip and the indexing stripe associated with said strip during each cycle of said deflection; means for deriving a signal in response to impingement of said beam on said indexing stripes; and means for utilizing said derived signal to control the rate of beam deflection in said first direction.

4. In a cathode ray tubedisplay system, means for producing a signal comprising successive portions representative of diierent intelligence components occurring in a predetermined order and recurring at a predetermined rate; a cathode ray tube for producing visible indications of the intelligence represented by said signal, said tube comprising a screen and means for proj eeting an electron beam toward said screen; means for deiiecting said beam in first and second mutually perpendicular directions across said screen and at rates such as to trace successively a plurality of substantially parallel paths upon said screen; a plurality of phosphor strips, each disposed longitudinally of one of said beam paths upon said screen; a plurality of indexing stripes, each associated with one of said phosphor stripes and disposed substantially parallel thereto; means for producing cyclical deection of said beam across said screen in said nrst direction at a rate substantially equal to said rate of recurrence of particular portions of said signal and of an amplitude suiici'ent to cause said beam to traverse the Width of a phosphor strip and the indexing stripe associated with said strip during each cycle of said deflection; means for deriving a signal in response to impingement of said beam on said indexing stripes; and means for utilizing said derived signal to control the rate of beam deflection in said first direction.

5. In a cathode ray tube display system: means for producing a signal having successive portions representative of diierent intelligence components occurring in a predetermined order and recurring at a predetermined rate; a cathode ray tube for producing visi-ble lindications of the intelligence represented by said signal, said tube comprising a screen, means for projecting an electron beam toward said screen, and means responsive to said signal to control the intensity of said beam, said screen having a plurality of substantially parallel phosphor strips and a plurality of indexing stripes, each associated with one of said strips and disposed substantially parallel thereto; means for producing successive deiiections of-said beam longitudinally of different ones oi said phosphor strips at such a rate as to cause said beam to traverse only a fraction of the length of a particular strip during one cycle of said signal; means for producing cyclically recurren-t deection's -of said beam transversely of said phosphor strips at a, rate substantially equal to the said rate of recurrenceof signal portions and of an amplitude sucient to cause said beam to traversethe width o f a phosphor strip and its :associated indexing stripe- #during eachl -fcycle fof 'sa-id transverse deflectionsmeans. lor lderiving 4a signalin lresponse to imp'ingement. of said electron beam on sai'dl indexing stripes; and means for utilizing saldi-.derived signal =to :control the denection-ofsaidbeamftransverselylof said phospli-or strips.

6i. 'In acathode ray tube display system: means for producingV a -signal'fhaving 'successive portions representative -of different intelligence components occurring in a predetermined-,order and recurring '-at a vprede'termimed Tate; a cathode :ray

itube for producing visible indicationsof the lintelligence represented Iby saidr signal, said tube associated with one of said -strips and disposed substantially parallel thereto; means vfor producing successive vdeflections of said beam longi- -tudinally'o'f d-iierentfones of said phosphor strips at such a-rate'fas'to cause said beam to tra-verse only/a fraction of the length of a particular strip during one Icycle of said signal; means for producing cyclicalfly` Irecurrent deflections of said beam transversely o'f phosphor strips at a rate Asubstan'tiz'allly'equal 1to the said rate of recurrence of signal portions and of -an amplitude sufllc'ientfto 'cause-'sai'dbeam to traverse the Width vof a phosphornstrip and its -associated indexing stripe vduring'each cycle of said transverse deection; means fior: dervingasignal in response to impingement of said electron `beam on said indeXingstripex-means responsive to variations inthe timesof occurrence of the said derived signal to produce 'a control signal; and means for utilizing said control signal to :control the deilection of said beam transversely of said phosphor strips.

7. vIn a cathoderay tube display system: means for producing arsignalhaving Asuccessive portions representative of different intelligence components occurring a vpredetermined order and recurring at. a'predetermined rate; a ycathode ray tube `forproducing visible indieations of the intelligence represented by said signal, said tube comprising "a screen, means or projecting an electron-beam toward said screenfand--means responsive to said signal to rcontrol the intensity 'ol' said beam, said screenf having a plurality of substantially :parallel phosphor strips and a plurality 'of' indexing stripes,feach associated with one of said strips. .and "disposed substantially parallel' thereto; means-for-iproducing successive 'dellections of said -beam longitudinally of'dierent ones o'fsai-d phosphor'strips at such a rate as to cause said beamito traverse only a fraction of the length of `a particular strip during one cycle ofsai'dsignal; means Efor: producing cyclically recurrent deflections-of said'beam transverselyo'f said phosphorstrips at a rate substantially equal to vthesaid-rate of recurren-ce of ysignal portions and -fof an amplitude suflicient to cause saidbeam totraversey the width of a phosphor strip'anditsassocated'indexing stripe during each cycle of said transverse deflection; means vfor deriving apulsesignal in response to each impingementofsaid electron beam on `any one ,of saldiindexingstripes; `means supplied with saidderived pulse signals and responsive thereto 'to produce a ,continuoussmusoidal signal hav- 'ing-"substantially theesame frequency and phase 1B charzwteristlcsv as the said pulse signals; and means for sensing variations in the phase of said sinusoidal signal and for controlling the deflection of said'beam transversely of said phosphor strips in proportion to said variations.

8. In a cathode ray tube display system: means for producing a first signal having successive portions representative of different intelligence components occurring in a predetermined order and recurring at a predetermined rate; a source of a second signal Whose phase and frequency are respectively indicative of the times of occurrence and the rate of recurrence of the said intelligence representative portions of said rst signal; a cathode ray tube for producing Visible indications of the intelligence represented by said first signal, said tube comprising a screen, means for projecting an electron beam toward said screen, and means responsive to said signal to control the intensity of said beam, said screen having a plurality of substantially parallel phosphor strips and a plurality of indexing stripes, each associated With one of said strips and disposed substantially parallel thereto; means for producing successive deflections of said beam longitudinally of dilerent ones of said phosphor strips at such a rate as to cause saidbeam to traverse only a fraction of the length of a particular strip during one cycle of, said first signal; means for producing cyclically recurrent deflections of said beam ransversely of saidphosphor. strips atarate substantially equal to .the said rate of recurrence of signal portions .and of an amplitude sulcient to cause said beam to traverse the Width of a phosphor stri-p and'its associated indexing stripe during each cycle of said transverse dellections; means for deriving va signal in response to impingement. of said electron beam on said indexing stripes; means supplied with said second signaland with said derived signal and responsive to .relative phase .variations therebetween to produce a control signal proportional to said variations; .and,means for utilizing said controlsignal to control Athe deflection of said beam transversely of said phosphor strips.

9. In a cathode ray tubeidisplay system: means for producing aA signal having successive portions representative of intelligence respecting different color components occurring in a predetermined order and recurring at a predetermined rate; a cathode ray tube for producing visible indications of said color components, said tube comprising aser-een, means for projecting an electron beam toward said screen,.and means responsive to said intelligence signal to control the intensity or" said. beam, said screen including a plurality of substantially parallelly disposed groupspf phosphor stripes, each of said groups including different stripes responsive to electron beam impingement to produce light of said different colors, diflerent color stripes being disposed in the same order Within each said group in which thessaid, successive signal vportions are representative of diierent color components, and a plurality of indexing stripes, each associated with one of said groups of phosphor stripes and disposed substantially parallel thereto; means for-producing successive deflections of said beam longitudinally of different ones of said phosphor stripe groups atsuch a rate as to cause said beam to traverse-only a portion-ofthe length of' a; particular group during one cycle of said signal; means for producing cyclicallyvrecurrent deflections offsaid beam transversely of said phosphor stripe groups Aat a nrate A1substantially:equal-:to `the said rate of recurrence of signal portions and of an amplitude suiicient to cause said beam to traverse all the phosphor stripes of a group and the indexing stripe associated therewith during each cycle of said transverse deflections; means for deriving a signal in response to impingement of said electron beam upon said indexing stripes; and means for utilizing said derived signal to control the deflection of said beam transversely of said groups.

10. In a cathode ray tube display system: means for producing a signal having successive portions representative of red, green and blue color components occurring in a predetermined order and recurring at a predetermined rate; a cathode ray tube for producing visible indications of said intelligence, said tube comprising a screen, means for projecting an electron beam toward said screen and means responsive to said intelligence signal to modulate the intensity of said beam, said screen including a plurality of substantially parallelly disposed groups of phosphor stripes, each group comprising a red, a. green and a blue light emissive stripe arranged in the same order as the said order of occurrence of color representative signal portions, and a plurality of indexing stripes, each associated with one of said groups of phosphor stripes and disposed substantially parallel thereto; means for producing successive deections of said beam across said screen longitudinally of diierent ones of said phosphor stripe groups; means for producing cyclically recurrent deections of said beam transversely of said groups at a rate substantially equal to the said rate of recurrence of signal portions, of amplitude such as to traverse a red, a. green and blue light emissive phosphor stripe and an indexing stripe during each cycle of said last-named deections, and in such sense as to traverse said stripes in the order in which the said signal portions are representative of different color components; means for deriving a signal in response to impingement of said electron beam on said indexing stripes; and means for utilizing said derived signal to control the deection of said beam transversely of said phosphor stripes.

ROBERT C. MOORE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,431,115 Goldsmith Nov. 18, 1947 2,530,431 Huiman Nov. 21,1950 2,587,074 Szaklai Feb. 26, 1952 

